In manufacturing a semiconductor device, such as an IC or LSI, a multilayer circuit pattern is superpose-transferred onto a wafer. In some cases, different exposure apparatuses are used due to a difference in accuracy required in respective layers, and superposition accuracy (matching accuracy) must be maintained among different exposure apparatuses. Especially, in an exposure apparatus based on a global alignment method of measuring plural superposition marks transferred on a wafer so as to correct a positional shift to a wafer xy plane (a plane vertical to an optical axis of a projection optical system (defined with mutually orthogonal x and y axes)) and a rotational shift about a θ axis (rotation about an axis parallel to the optical axis of the projection optical system (z axis orthogonal to the xy plane)), the following adjustment operations are performed.
First adjustment item: adjustment of xy coordinate parallelism between the reticle projection image and wafer stage.
Second adjustment item: adjustment of xy axis rectangularity of the wafer stage.
Third adjustment item: adjustment of linearity of xy axes of the wafer stage.
Fourth adjustment item: adjustment of θ axis stability of the wafer stage.
Particularly, in a one-shot full exposure apparatus, regarding the third and fourth adjustment items, the linearity of the xy axes and the stability of the θ axis of the wafer stage are measured and corrected by the method proposed by the present applicant, i.e., measuring superposition marks formed by performing exposure and transfer such that adjacent shots partially overlap each other, and performing arithmetic processing at once on these measured data (for example, see Japanese Published Unexamined Patent Application No. 2000-299278).
For example, exposure is repeated such that adjacent shots in x and y directions partially overlap each other, as shown in FIG. 1, that is, a shot 31, a shot 32 adjacent to the shot 31 in the x direction, and a shot 33 adjacent to the shots 31 and 32 in the y direction, partially overlap each other, as shown in FIG. 2. Two superposition marks 34, 35 are formed in the x-direction overlap area, and two superposition marks 36, 37, in the y-direction overlap area. Then, relative distances dx, dy, and a relative rotational angle dθ in the respective shots are obtained from the data obtained from measurement of the relative positions of the overlapping marks by the least square method.
However, in the method disclosed in th above Japanese Published Unexamined Patent Application No. 2000-299278, in the case of a scanning projection exposure apparatus (so-called a scanner) to perform transfer by one-shot exposure using a slit shot, even if two or more superposition marks are formed in an area where shorter sides are adjacent, the influence of a relative rotational angle obtained from the difference among these marks is small and the linearity of the xy axes and the stability of the θ axis of the wafer stage cannot be measured with high accuracy.